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<title>Repetition Generator Directive (repeat[])</title>
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<div class="titlepage"><div><div><h5 class="title">
<a name="spirit.karma.reference.directive.repeat"></a><a class="link" href="repeat.html" title="Repetition Generator Directive (repeat[])">Repetition
          Generator Directive (<code class="computeroutput"><span class="identifier">repeat</span><span class="special">[]</span></code>)</a>
</h5></div></div></div>
<h6>
<a name="spirit.karma.reference.directive.repeat.h0"></a>
            <span class="phrase"><a name="spirit.karma.reference.directive.repeat.description"></a></span><a class="link" href="repeat.html#spirit.karma.reference.directive.repeat.description">Description</a>
          </h6>
<p>
            The repetition directive allows to repeat an arbitrary generator expression
            while optionally specifying the lower and upper repetition counts. It
            provides a more powerful and flexible mechanism for repeating a generator.
            There are grammars that are impractical and cumbersome, if not impossible,
            for the basic EBNF iteration syntax ( <a class="link" href="../operator/kleene.html" title="Kleene Star Generator (*a)">unary
            <code class="computeroutput"><span class="char">'*'</span></code></a> and the <a class="link" href="../operator/plus.html" title="Plus Generator (+a)">unary
            <code class="computeroutput"><span class="char">'+'</span></code></a>) to specify. Examples:
          </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
                A file name may have a maximum of 255 characters only.
              </li>
<li class="listitem">
                A specific bitmap file format has exactly 4096 RGB color information.
              </li>
<li class="listitem">
                A 256 bit binary string (1..256 1s or 0s).
              </li>
</ul></div>
<h6>
<a name="spirit.karma.reference.directive.repeat.h1"></a>
            <span class="phrase"><a name="spirit.karma.reference.directive.repeat.header"></a></span><a class="link" href="repeat.html#spirit.karma.reference.directive.repeat.header">Header</a>
          </h6>
<pre class="programlisting"><span class="comment">// forwards to &lt;boost/spirit/home/karma/directive/repeat.hpp&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">karma_repeat</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
</pre>
<p>
            Also, see <a class="link" href="../../../structure/include.html" title="Include">Include Structure</a>.
          </p>
<h6>
<a name="spirit.karma.reference.directive.repeat.h2"></a>
            <span class="phrase"><a name="spirit.karma.reference.directive.repeat.namespace"></a></span><a class="link" href="repeat.html#spirit.karma.reference.directive.repeat.namespace">Namespace</a>
          </h6>
<div class="informaltable"><table class="table">
<colgroup><col></colgroup>
<thead><tr><th>
                    <p>
                      Name
                    </p>
                  </th></tr></thead>
<tbody>
<tr><td>
                    <p>
                      <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">repeat</span> <span class="comment">//
                      alias: boost::spirit::karma::repeat</span></code>
                    </p>
                  </td></tr>
<tr><td>
                    <p>
                      <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">inf</span> <span class="comment">// alias:
                      boost::spirit::karma::inf</span></code>
                    </p>
                  </td></tr>
</tbody>
</table></div>
<h6>
<a name="spirit.karma.reference.directive.repeat.h3"></a>
            <span class="phrase"><a name="spirit.karma.reference.directive.repeat.model_of"></a></span><a class="link" href="repeat.html#spirit.karma.reference.directive.repeat.model_of">Model of</a>
          </h6>
<div class="blockquote"><blockquote class="blockquote"><p>
              <a class="link" href="../generator_concepts/unarygenerator.html" title="UnaryGenerator"><code class="computeroutput"><span class="identifier">UnaryGenerator</span></code></a>
            </p></blockquote></div>
<div class="variablelist">
<p class="title"><b>Notation</b></p>
<dl class="variablelist">
<dt><span class="term"><code class="computeroutput"><span class="identifier">a</span></code></span></dt>
<dd><p>
                  A generator object
                </p></dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">num</span><span class="special">,</span>
              <span class="identifier">num1</span><span class="special">,</span>
              <span class="identifier">num2</span></code></span></dt>
<dd><p>
                  Numeric literals, any unsigned integer value, or a <a class="link" href="../basics.html#spirit.karma.reference.basics.lazy_argument">Lazy
                  Argument</a> that evaluates to an unsigned integer value
                </p></dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">inf</span></code></span></dt>
<dd><p>
                  Placeholder expression standing for 'no upper repeat limit'
                </p></dd>
</dl>
</div>
<h6>
<a name="spirit.karma.reference.directive.repeat.h4"></a>
            <span class="phrase"><a name="spirit.karma.reference.directive.repeat.expression_semantics"></a></span><a class="link" href="repeat.html#spirit.karma.reference.directive.repeat.expression_semantics">Expression
            Semantics</a>
          </h6>
<p>
            Semantics of an expression is defined only where it differs from, or
            is not defined in <a class="link" href="../generator_concepts/unarygenerator.html" title="UnaryGenerator"><code class="computeroutput"><span class="identifier">UnaryGenerator</span></code></a>.
          </p>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
                    <p>
                      Expression
                    </p>
                  </th>
<th>
                    <p>
                      Semantics
                    </p>
                  </th>
</tr></thead>
<tbody>
<tr>
<td>
                    <p>
                      <code class="computeroutput"><span class="identifier">repeat</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code>
                    </p>
                  </td>
<td>
                    <p>
                      Repeat the generator <code class="computeroutput"><span class="identifier">a</span></code>
                      zero or more times. This generator succeeds as long as its
                      embedded generator <code class="computeroutput"><span class="identifier">a</span></code>
                      does not fail (except if the underlying output stream reports
                      an error). This variant of <code class="computeroutput"><span class="identifier">repeat</span><span class="special">[]</span></code> is semantically equivalent
                      to the <a class="link" href="../operator/kleene.html" title="Kleene Star Generator (*a)">Kleene
                      Star operator <code class="computeroutput"><span class="special">*</span><span class="identifier">a</span></code></a>
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      <code class="computeroutput"><span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span></code>
                    </p>
                  </td>
<td>
                    <p>
                      Repeat the generator <code class="computeroutput"><span class="identifier">a</span></code>
                      exactly <code class="computeroutput"><span class="identifier">num</span></code>
                      times. This generator succeeds as long as its embedded generator
                      <code class="computeroutput"><span class="identifier">a</span></code> does not
                      fail and as long as the associated attribute (container) contains
                      at least <code class="computeroutput"><span class="identifier">num</span></code>
                      elements (unless the underlying output stream reports an error).
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      <code class="computeroutput"><span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num1</span><span class="special">,</span>
                      <span class="identifier">num2</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span></code>
                    </p>
                  </td>
<td>
                    <p>
                      Repeat the generator <code class="computeroutput"><span class="identifier">a</span></code>
                      at least <code class="computeroutput"><span class="identifier">num1</span></code>
                      times but not more than <code class="computeroutput"><span class="identifier">num2</span></code>
                      times. This generator succeeds as long as its embedded generator
                      <code class="computeroutput"><span class="identifier">a</span></code> does not
                      fail and as long as the associated attribute (container) contains
                      at least <code class="computeroutput"><span class="identifier">num1</span></code>
                      elements (unless the underlying output stream reports an error).
                      If the associated attribute (container) does contain more than
                      <code class="computeroutput"><span class="identifier">num2</span></code> elements,
                      this directive limits the repeat count to <code class="computeroutput"><span class="identifier">num2</span></code>.
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      <code class="computeroutput"><span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num</span><span class="special">,</span>
                      <span class="identifier">inf</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span></code>
                    </p>
                  </td>
<td>
                    <p>
                      Repeat the generator <code class="computeroutput"><span class="identifier">a</span></code>
                      at least <code class="computeroutput"><span class="identifier">num1</span></code>
                      times. No upper limit for the repeat count is set. This generator
                      succeeds as long as its embedded generator <code class="computeroutput"><span class="identifier">a</span></code>
                      does not fail and as long as the associated attribute (container)
                      contains at least <code class="computeroutput"><span class="identifier">num</span></code>
                      elements (unless the underlying output stream reports an error).
                    </p>
                  </td>
</tr>
</tbody>
</table></div>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
              All failing iterations of the embedded generator will consume one element
              from the supplied attribute. The overall <code class="computeroutput"><span class="identifier">repeat</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code> will succeed as long as the iteration
              criteria (number of successful invocations of the embedded generator)
              is fulfilled (unless the underlying output stream reports an error).
            </p></td></tr>
</table></div>
<h6>
<a name="spirit.karma.reference.directive.repeat.h5"></a>
            <span class="phrase"><a name="spirit.karma.reference.directive.repeat.attributes"></a></span><a class="link" href="repeat.html#spirit.karma.reference.directive.repeat.attributes">Attributes</a>
          </h6>
<p>
            See <a class="link" href="../../quick_reference/compound_attribute_rules.html#spirit.karma.quick_reference.compound_attribute_rules.notation">Compound
            Attribute Notation</a>.
          </p>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
                    <p>
                      Expression
                    </p>
                  </th>
<th>
                    <p>
                      Attribute
                    </p>
                  </th>
</tr></thead>
<tbody>
<tr>
<td>
                    <p>
                      <code class="computeroutput"><span class="identifier">repeat</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code>
                    </p>
                  </td>
<td>
                    <p>
</p>
<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">a</span><span class="special">:</span> <span class="identifier">A</span> <span class="special">--&gt;</span> <span class="identifier">repeat</span><span class="special">[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">vector</span><span class="special">&lt;</span><span class="identifier">A</span><span class="special">&gt;</span>
<span class="identifier">a</span><span class="special">:</span> <span class="identifier">Unused</span> <span class="special">--&gt;</span> <span class="identifier">repeat</span><span class="special">[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">Unused</span></pre>
<p>
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      <code class="computeroutput"><span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span></code>
                    </p>
                  </td>
<td>
                    <p>
</p>
<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">a</span><span class="special">:</span> <span class="identifier">A</span> <span class="special">--&gt;</span> <span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">vector</span><span class="special">&lt;</span><span class="identifier">A</span><span class="special">&gt;</span>
<span class="identifier">a</span><span class="special">:</span> <span class="identifier">Unused</span> <span class="special">--&gt;</span> <span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">Unused</span></pre>
<p>
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      <code class="computeroutput"><span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num1</span><span class="special">,</span>
                      <span class="identifier">num2</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span></code>
                    </p>
                  </td>
<td>
                    <p>
</p>
<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">a</span><span class="special">:</span> <span class="identifier">A</span> <span class="special">--&gt;</span> <span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num1</span><span class="special">,</span> <span class="identifier">num2</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">vector</span><span class="special">&lt;</span><span class="identifier">A</span><span class="special">&gt;</span>
<span class="identifier">a</span><span class="special">:</span> <span class="identifier">Unused</span> <span class="special">--&gt;</span> <span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num1</span><span class="special">,</span> <span class="identifier">num2</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">Unused</span></pre>
<p>
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      <code class="computeroutput"><span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num</span><span class="special">,</span>
                      <span class="identifier">inf</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]</span></code>
                    </p>
                  </td>
<td>
                    <p>
</p>
<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">a</span><span class="special">:</span> <span class="identifier">A</span> <span class="special">--&gt;</span> <span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num</span><span class="special">,</span> <span class="identifier">inf</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">vector</span><span class="special">&lt;</span><span class="identifier">A</span><span class="special">&gt;</span>
<span class="identifier">a</span><span class="special">:</span> <span class="identifier">Unused</span> <span class="special">--&gt;</span> <span class="identifier">repeat</span><span class="special">(</span><span class="identifier">num</span><span class="special">,</span> <span class="identifier">inf</span><span class="special">)[</span><span class="identifier">a</span><span class="special">]:</span> <span class="identifier">Unused</span></pre>
<p>
                    </p>
                  </td>
</tr>
</tbody>
</table></div>
<div class="important"><table border="0" summary="Important">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Important]" src="../../../../images/important.png"></td>
<th align="left">Important</th>
</tr>
<tr><td align="left" valign="top">
<p>
              The table above uses <code class="computeroutput"><span class="identifier">vector</span><span class="special">&lt;</span><span class="identifier">A</span><span class="special">&gt;</span></code> as placeholders only.
            </p>
<p>
              The notation of <code class="computeroutput"><span class="identifier">vector</span><span class="special">&lt;</span><span class="identifier">A</span><span class="special">&gt;</span></code> stands for <span class="emphasis"><em>any STL container</em></span>
              holding elements of type <code class="computeroutput"><span class="identifier">A</span></code>.
            </p>
</td></tr>
</table></div>
<p>
            It is important to note, that the <code class="computeroutput"><span class="identifier">repeat</span><span class="special">[]</span></code> directive does not perform any buffering
            of the output generated by its embedded elements. That means that any
            failing element generator might have already generated some output, which
            is <span class="emphasis"><em>not</em></span> rolled back.
          </p>
<div class="tip"><table border="0" summary="Tip">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Tip]" src="../../../../images/tip.png"></td>
<th align="left">Tip</th>
</tr>
<tr><td align="left" valign="top">
<p>
              The simplest way to force a <code class="computeroutput"><span class="identifier">repeat</span><span class="special">[]</span></code> directive to behave as if it did
              buffering is to wrap it into a buffering directive (see <a class="link" href="buffer.html" title="Generator Directive for Temporary Output Buffering (buffer[])"><code class="computeroutput"><span class="identifier">buffer</span></code></a>):
            </p>
<p>
</p>
<pre class="programlisting"><span class="identifier">buffer</span><span class="special">[</span><span class="identifier">repeat</span><span class="special">[</span><span class="identifier">a</span><span class="special">]]</span></pre>
<p>
            </p>
<p>
              which will <span class="emphasis"><em>not</em></span> generate any output in case of
              a failing generator <code class="computeroutput"><span class="identifier">repeat</span><span class="special">[</span><span class="identifier">a</span><span class="special">]</span></code>. The expression:
            </p>
<p>
</p>
<pre class="programlisting"><span class="identifier">repeat</span><span class="special">[</span><span class="identifier">buffer</span><span class="special">[</span><span class="identifier">a</span><span class="special">]]</span></pre>
<p>
            </p>
<p>
              will not generate any partial output from a generator <code class="computeroutput"><span class="identifier">a</span></code> if it fails generating in the middle
              of its output. The overall expression will still generate the output
              as produced by all succeeded invocations of the generator <code class="computeroutput"><span class="identifier">a</span></code>.
            </p>
</td></tr>
</table></div>
<h6>
<a name="spirit.karma.reference.directive.repeat.h6"></a>
            <span class="phrase"><a name="spirit.karma.reference.directive.repeat.complexity"></a></span><a class="link" href="repeat.html#spirit.karma.reference.directive.repeat.complexity">Complexity</a>
          </h6>
<div class="blockquote"><blockquote class="blockquote"><p>
              The overall complexity of the repetition generator is defined by the
              complexity of its embedded generator. The complexity of the repeat
              itself is O(N), where N is the number of repetitions to execute.
            </p></blockquote></div>
<h6>
<a name="spirit.karma.reference.directive.repeat.h7"></a>
            <span class="phrase"><a name="spirit.karma.reference.directive.repeat.example"></a></span><a class="link" href="repeat.html#spirit.karma.reference.directive.repeat.example">Example</a>
          </h6>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
              The test harness for the example(s) below is presented in the <a class="link" href="../basics.html#spirit.karma.reference.basics.examples">Basics Examples</a>
              section.
            </p></td></tr>
</table></div>
<p>
            Some includes:
          </p>
<p>
</p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">karma</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">support_utree</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">phoenix_core</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">phoenix_operator</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fusion</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">std_pair</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">iostream</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">string</span><span class="special">&gt;</span>
</pre>
<p>
          </p>
<p>
            Some using declarations:
          </p>
<p>
</p>
<pre class="programlisting"><span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">karma</span><span class="special">::</span><span class="identifier">double_</span><span class="special">;</span>
<span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">karma</span><span class="special">::</span><span class="identifier">repeat</span><span class="special">;</span>
</pre>
<p>
          </p>
<p>
            Basic usage of <code class="computeroutput"><span class="identifier">repeat</span></code>
            generator directive:
          </p>
<p>
</p>
<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">&gt;</span> <span class="identifier">v</span><span class="special">;</span>
<span class="identifier">v</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="number">1.0</span><span class="special">);</span>
<span class="identifier">v</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="number">2.0</span><span class="special">);</span>
<span class="identifier">v</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="number">3.0</span><span class="special">);</span>

<span class="identifier">test_generator_attr</span><span class="special">(</span><span class="string">"[1.0][2.0][3.0]"</span><span class="special">,</span> <span class="identifier">repeat</span><span class="special">[</span><span class="char">'['</span> <span class="special">&lt;&lt;</span> <span class="identifier">double_</span> <span class="special">&lt;&lt;</span> <span class="char">']'</span><span class="special">],</span> <span class="identifier">v</span><span class="special">);</span>
<span class="identifier">test_generator_attr</span><span class="special">(</span><span class="string">"[1.0][2.0]"</span><span class="special">,</span> <span class="identifier">repeat</span><span class="special">(</span><span class="number">2</span><span class="special">)[</span><span class="char">'['</span> <span class="special">&lt;&lt;</span> <span class="identifier">double_</span> <span class="special">&lt;&lt;</span> <span class="char">']'</span><span class="special">],</span> <span class="identifier">v</span><span class="special">);</span>

<span class="comment">// fails because of insufficient number of items</span>
<span class="identifier">test_generator_attr</span><span class="special">(</span><span class="string">""</span><span class="special">,</span> <span class="identifier">repeat</span><span class="special">(</span><span class="number">4</span><span class="special">)[</span><span class="char">'['</span> <span class="special">&lt;&lt;</span> <span class="identifier">double_</span> <span class="special">&lt;&lt;</span> <span class="char">']'</span><span class="special">],</span> <span class="identifier">v</span><span class="special">);</span>
</pre>
<p>
          </p>
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        Distributed under the Boost Software License, Version 1.0. (See accompanying
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